Spatial modulation strategy for construction of artificial polar skyrmion arrays in ferroelectrics

Polar skyrmions are unique particlelike swirling polarization textures with nontrivial topology. So far, they have mainly been discovered in ferroelectric-insulator superlattices and multilayers, showing a densely packed and liquidlike state that suffers strong interactions with neighbors. This makes it challenging to develop storage and logic devices based on polar skyrmions, and limits the exploration of the potentially unique properties of polar skyrmion lattices. An important and interesting question, therefore, is the following: Can we construct artificial polar skyrmion arrays with regular spatial distribution and weak correlation in ferroelectrics? Here, via phase-field simulations, we demonstrate a spatial modulation strategy for the construction of regularly distributed and weakly correlated artificial polar skyrmion arrays in ferroelectric thin film. The crossbar electrode pattern on the top surface of the ferroelectric thin film is introduced in the simulated model to create the spatial modulation effect. The stability of the artificial polar skyrmion arrays is summarized by the use of phase diagrams. These polar skyrmions are illustrated to be individually controllable by local electric and mechanical stimuli. Moreover, a mechanism of weak correlation between the skyrmions is elucidated, and a dimerization phenomenon of artificial polar skyrmion arrays akin to the antiferroelectric distortion is revealed. Our work, therefore, provides a new approach to constructing intriguing polar topological textures in ferroelectrics and offers promising possibilities for developing devices based on polar topology.